Selective catalytic reduction (SCR) systems have been used to reduce automotive emissions. However, SCR systems may rely on the availability and make-up of a reductant, such as urea, stored in an on-board storage device. For example, the on-board storage device may become substantially empty. Alternately or in addition, a vehicle operator may introduce an ineffective fluid to a reductant storage device.
One way to detect the availability of a reductant attaches various sensors to the on-board storage device to independently detect the availability of reductant. For example, a sensor, such as a level sensor, can be used to detect a physical condition of the on-board storage device. However, the sensor may detect a false empty condition when the vehicle is traveling on an incline, and the stored fluid accumulates at the downhill region of the on-board storage device. Further, the sensor may detect that fluid may be available in the on-board storage device although the fluid may not be a reductant. In yet another example, a sensor, such as a thermal conductivity sensor, can detect a property of the stored fluid to verify that an appropriate reductant may be stored in the on-board storage device. However, erroneous detection of a reductant may occur when a non-urea solution (or reduced-urea solution) with the same or similar property may be introduced to the on-board storage device.
The inventors herein have realized that a logic driven method may be implemented by coordinating a physical condition associated with a reductant storage device, wherein the physical condition may correspond to a measure of liquid stored in the reductant storage device, with a characteristic of a fluid stored in the reductant storage device to determine the availability and make-up of the stored fluid, wherein at least one of the physical condition and the property of the stored fluid is determined by a plurality of sensors, and adjusting engine operation based on said coordinating the condition associated with the reductant storage device with the property of the stored fluid. Such methods of coordinating pluralities of conditions and properties associated with the emission control system may facilitate delivery of a reductant to the emission control device.